Apparatus and methods for mapping and ablation in electrophysiology procedures

ABSTRACT

An electrophysiology catheter and method of use for mapping and ablation procedures. The catheter includes a braided conductive member at its distal end that can be radially expanded. The catheter can be used in endocardial and epicardial mapping and ablation procedures.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.10/939,630, filed Sep. 13, 2004, which is a divisional of U.S.application Ser. No. 09/845,022, filed Apr. 27, 2001, both of which areentitled APPARATUS AND METHODS FOR MAPPING AND ABLATION INELECTROPHYSIOLOGY PROCEDURES, both of which are hereby incorporatedherein by reference in their entirety, and which, in turn, claim thebenefit of U.S. Provisional Application Ser. No. 60/261,015 entitledHIGH DENSITY MAPPING AND ABLATION CATHETER AND METHOD OF USE, filed Jan.11, 2001; U.S. Provisional Application Ser. No. 60/204,457 entitledMETHOD FOR CREATING ANNULAR EPICARDIAL LESIONS AT THE OSTIA OF THEPULMONARY VEINS, filed on May 16, 2000; U.S. Provisional ApplicationSer. No. 60/204,482 entitled METHOD AND DEVICE FOR CREATING ANNULARENDOCARDIAL LESIONS AT THE OSTIA OF THE PULMONARY VEINS, filed May 16,2000; and U.S. Provisional Application Ser. No. 60/201,445 entitledTRANSMURAL CIRCUMFERENTIAL LESIONS MADE AT CANINE PV OSTIUM BYEXPANDABLE MESH ELECTRODES IN VIVO, filed May 3, 2000, whichapplications are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to medical devices for performing mapping andablation procedures. More particularly, the invention relates to methodsand apparatus for mapping and ablating at or near the ostia of thepulmonary veins or coronary sinus.

2. Discussion of the Related Art

The human heart is a very complex organ, which relies on both musclecontraction and electrical impulses to function properly. The electricalimpulses travel through the heart walls, first through the atria andthen the ventricles, causing the corresponding muscle tissue in theatria and ventricles to contract. Thus, the atria contract first,followed by the ventricles. This order is essential for properfunctioning of the heart.

Over time, the electrical impulses traveling through the heart can beginto travel in improper directions, thereby causing the heart chambers tocontract at improper times. Such a condition is generally termed acardiac arrhythmia, and can take many different forms. When the chamberscontract at improper times, the amount of blood pumped by the heartdecreases, which can result in premature death of the person.

Techniques have been developed which are used to locate cardiac regionsresponsible for the cardiac arrhythmia, and also to disable theshort-circuit function of these areas. According to these techniques,electrical energy is applied to a portion of the heart tissue to ablatethat tissue and produce scars which interrupt the reentrant conductionpathways or terminate the focal initiation. The regions to be ablatedare usually first determined by endocardial mapping techniques. Mappingtypically involves percutaneously introducing a catheter having one ormore electrodes into the patient, passing the catheter through a bloodvessel (e.g. the femoral vein or artery) and into an endocardial site(e.g., the atrium or ventricle of the heart), and deliberately inducingan arrhythmia so that a continuous, simultaneous recording can be madewith a multichannel recorder at each of several different endocardialpositions. When an arrythormogenic focus or inappropriate circuit islocated, as indicated in the electrocardiogram recording, it is markedby various imaging or localization means so that cardiac arrhythmiasemanating from that region can be blocked by ablating tissue. Anablation catheter with one or more electrodes can then transmitelectrical energy to the tissue adjacent the electrode to create alesion in the tissue. One or more suitably positioned lesions willtypically create a region of necrotic tissue which serves to disable thepropagation of the errant impulse caused by the arrythromogenic focus.Ablation is carried out by applying energy to the catheter electrodes.The ablation energy can be, for example, RF, DC, ultrasound, microwave,or laser radiation.

Atrial fibrillation together with atrial flutter are the most commonsustained arrhythmias found in clinical practice.

Current understanding is that atrial fibrillation is frequentlyinitiated by a focal trigger from the orifice of or within one of thepulmonary veins. Though mapping and ablation of these triggers appearsto be curative in patients with paroxysmal atrial fibrillation, thereare a number of limitations to ablating focal triggers via mapping andablating the earliest site of activation with a “point” radiofrequencylesion. One way to circumvent these limitations is to determineprecisely the point of earliest activation. Once the point of earliestactivation is identified, a lesion can be generated to electricallyisolate the trigger with a lesion; firing from within those veins wouldthen be eliminated or unable to reach the body of the atrium, and thuscould not trigger atrial fibrillation.

Another method to treat focal arrhythmias is to create a continuous,annular lesion around the ostia (i.e., the openings) of either the veinsor the arteries leading to or from the atria thus “corralling” thesignals emanating from any points distal to the annular lesion.Conventional techniques include applying multiple point sources aroundthe ostia in an effort to create such a continuous lesion. Such atechnique is relatively involved, and requires significant skill andattention from the clinician performing the procedures.

Another source of arrhythmias may be from reentrant circuits in themyocardium itself. Such circuits may not necessarily be associated withvessel ostia, but may be interrupted by means of ablating tissue eitherwithin the circuit or circumscribing the region of the circuit. Itshould be noted that a complete ‘fence’ around a circuit or tissueregion is not always required in order to block the propagation of thearrhythmia; in many cases simply increasing the propagation path lengthfor a signal may be sufficient. Conventional means for establishing suchlesion ‘fences’ include a multiplicity of point-by-point lesions,dragging a single electrode across tissue while delivering energy, orcreating an enormous lesion intended to inactivate a substantive volumeof myocardial tissue.

Commonly-owned U.S. patent application Ser. No. 09/396,502, entitledApparatus For Creating A Continuous Annular Lesion, which is herebyincorporated by reference, discloses a medical device which is capableof ablating a continuous ring of tissue around the ostia of either veinsor arteries leading to or from the atria.

SUMMARY OF THE INVENTION

The present invention encompasses apparatus and methods for mappingelectrical activity within the heart. The present invention alsoencompasses methods and apparatus for creating lesions in the hearttissue (ablating) to create a region of necrotic tissue which serves todisable the propagation of errant electrical impulses caused by anarrhythmia.

In one embodiment, the present invention includes a medical deviceincluding a catheter having a braided conductive member at a distal endthereof, a mechanism for expanding the braided conductive member from anundeployed to a deployed position, and a mechanism for applying energyvia the braided conductive member to blood vessel.

In one embodiment, the medical device further includes a mechanism forirrigating the braided conductive member.

In another embodiment, the medical device further includes at least onereference electrode disposed on a shaft of the catheter.

In another embodiment, the medical device includes a mechanism forcontrolling the energy supplied to the braided conductive member.

In another embodiment, the medical device further includes a mechanismfor covering at least a portion of the braided conductive member whenthe braided conductive member is in the deployed position.

In another embodiment, at least a portion of the braided conductivemember has a coating applied thereto.

In another embodiment, the medical device includes a mechanism formeasuring temperature.

In another embodiment, the medical device includes a mechanism forsteering the catheter.

The invention also includes a method for treating cardiac arrhythmia,including the steps of introducing a catheter having a braidedconductive member at a distal end thereof into a blood vessel, expandingthe braided conductive member at a selected location in the blood vesselso that the braided conductive member contacts a wall of the bloodvessel, and applying energy to the wall of the blood vessel via thebraided conductive member to create a lesion in the blood vessel.

In another embodiment, the invention includes a method for treatingcardiac arrhythmia, including the steps of introducing a catheter into athoracic cavity of a patient, the catheter having a braided conductivemember at a distal end thereof, contacting an exterior wall of a bloodvessel in a vicinity of an ostium with the braided conductive member,and applying energy to the blood vessel via the braided conductivemember to create a lesion on the exterior wall of the blood vessel.

The braided conductive member may be a wire mesh.

The features and advantages of the present invention will be morereadily understood and apparent from the following detailed descriptionof the invention, which should be read in conjunction with theaccompanying drawings, and from the claims which are appended at the endof the Detailed Description.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are incorporated herein by reference and in whichlike elements have been given like references characters,

FIG. 1 illustrates an overview of a mapping and ablation catheter systemin accordance with the present invention;

FIGS. 2 and 3 illustrate further details of the catheter illustrated inFIG. 1;

FIGS. 4-7 illustrate further details of the braided conductive memberillustrated in FIGS. 2 and 3;

FIGS. 8-10A illustrate, among other things, temperature sensing in thepresent invention;

FIGS. 11-13 illustrate further details of the steering capabilities ofthe present invention;

FIGS. 14-17 illustrate further embodiments of the braided conductivemember;

FIGS. 18-19 illustrate the use of irrigation in connection with thepresent invention;

FIGS. 20A-20E illustrate the use of shrouds in the present invention;

FIG. 21 illustrates a guiding sheath that may be used in connection withthe present invention;

FIGS. 22-24 illustrate methods of using the present invention.

DETAILED DESCRIPTION

System Overview

Reference is now made to FIG. 1, which figure illustrates an overview ofa mapping and ablation catheter system in accordance with the presentinvention. The system includes a catheter 10 having a shaft portion 12,a control handle 14, and a connector portion 16. A controller 8 isconnected to connector portion 16 via cable 6. Ablation energy generator4 may be connected to controller 8 via cable 3. A recording device 2 maybe connected to controller 8 via cable 1. When used in an ablationapplication, controller 8 is used to control ablation energy provided byablation energy generator 4 to catheter 10. When used in a mappingapplication, controller 8 is used to process signals coming fromcatheter 10 and to provide these signals to recording device 2. Althoughillustrated as separate devices, recording device 2, ablation energygenerator 4, and controller 8 could be incorporated into a singledevice. In one embodiment, controller 8 may be a QUADRAPULSE RFCONTROLLER™ device available from CR Bard, Inc., Murray Hill, N.J.

In this description, various aspects and features of the presentinvention will be described. The various features of the invention arediscussed separately for clarity. One skilled in the art will appreciatethat the features may be selectively combined in a device depending uponthe particular application. Furthermore, any of the various features maybe incorporated in a catheter and associated method of use for eithermapping or ablation procedures.

Catheter Overview

Reference is now made to FIGS. 2-7, which figures illustrate oneembodiment of the present invention. The present invention generallyincludes a catheter and method of its use for mapping and ablation inelectrophysiology procedures. Catheter 10 includes a shaft portion 12, acontrol handle 14, and a connector portion 16. When used in mappingapplications, connector portion 16 is used to allow signal wires runningfrom the electrodes at the distal portion of the catheter to beconnected to a device for processing the electrical signals, such as arecording device.

Catheter 10 may be a steerable device. FIG. 2 illustrates the distal tipportion 18 being deflected by the mechanism contained within controlhandle 14. Control handle 14 may include a rotatable thumb wheel whichcan be used by a user to deflect the distal end of the catheter. Thethumb wheel (or any other suitable actuating device) is connected to oneor more pull wires which extend through shaft portion 12 and areconnected to the distal end 18 of the catheter at an off-axis location,whereby tension applied to one or more of the pull wires causes thedistal portion of the catheter to curve in a predetermined direction ordirections. U.S. Pat. Nos. 5,383,852, 5,462,527, and 5,611,777, whichare hereby incorporated by reference, illustrate various embodiments ofcontrol handle 14 that may be used for steering catheter 10.

Shaft portion 12 includes a distal tip portion 18, a first stop 20 andan inner member 22 connected to the first stop portion 20. Inner member22 may be a tubular member. Concentrically disposed about inner member22 is a first sheath 24 and a second sheath 26. Also concentricallydisposed about inner member 22 is a braided conductive member 28anchored at respective ends 30 and 32 to the first sheath 24 and thesecond sheath 26, respectively.

In operation, advancing the second sheath 26 distally over inner member22 causes the first sheath 24 to contact stop 20. Further distaladvancement of the second sheath 26 over inner member 22 causes thebraided conductive member 28 to expand radially to assume variousdiameters and/or a conical shape. FIG. 3 illustrates braided conductivemember 28 in an unexpanded (collapsed or “undeployed”) configuration.FIGS. 2 and 4 illustrate braided conductive member 28 in a partiallyexpanded condition. FIG. 1 illustrates braided conductive member 28radially expanded (“deployed”) to form a disk.

Alternatively, braided conductive member 28 can be radially expanded bymoving inner member 22 proximally with respect to the second sheath 26.

As another alternative, inner member 22 and distal tip portion 18 may bethe same shaft and stop 20 may be removed. In this configuration, sheath24 moves over the shaft in response to, for example, a mandrel insideshaft 22 and attached to sheath 24 in the manner described, for example,in U.S. Pat. No. 6,178,354, which is incorporated herein by reference.

As illustrated particularly in FIGS. 4 and 5 a third sheath 32 may beprovided. The third sheath serves to protect shaft portion 12 and inparticular braided conductive member 28 during manipulation through thepatient's vasculature. In addition, the third sheath 32 shields braidedconductive member 28 from the patient's tissue in the event ablationenergy is prematurely delivered to the braided conductive member 28.

The respective sheaths 24, 26, and 32 can be advanced and retracted overthe inner member 22, which may be a tubular member, in many differentmanners. Control handle 14 may be used. U.S. Pat. Nos. 5,383,852,5,462,527, and 5,611,777 illustrate examples of control handles that cancontrol sheaths 24, 26, and 32. As described in these incorporated byreference patents, control handle 14 may include a slide actuator whichis axially displaceable relative to the handle. The slide actuator maybe connected to one of the sheaths, for example, the second sheath 26 tocontrol the movement of the sheath 26 relative to inner member 22, todrive braided conductive member 28 between respective collapsed anddeployed positions, as previously described. Control handle 14 may alsoinclude a second slide actuator or other mechanism coupled to theretractable outer sheath 32 to selectively retract the sheath in aproximal direction with respect to the inner member 22.

Braided conductive member 28 is, in one embodiment of the invention, aplurality of interlaced, electrically conductive filaments 34. Braidedconductive member 28 may be a wire mesh. The filaments are flexible andcapable of being expanded radially outwardly from inner member 22. Thefilaments 34 are preferably formed of metallic elements havingrelatively small cross sectional diameters, such that the filaments canbe expanded radially outwardly. The filaments may be round, having adimension on the order of about 0.001-0.030 inches in diameter.Alternatively, the filaments may be flat, having a thickness on theorder of about 0.001-0.030 inches, and a width on the order of about0.001-0.030 inches. The filaments may be formed of Nitinol type wire.Alternatively, the filaments may include non metallic elements wovenwith metallic elements, with the non metallic elements providing supportto or separation of the metallic elements. A multiplicity of individualfilaments 34 may be provided in braided conductive member 28, forexample up to 300 or more filaments.

Each of the filaments 34 can be electrically isolated from each other byan insulation coating. This insulation coating may be, for example, apolyamide type material. A portion of the insulation on the outercircumferential surface 60 of braided conductive member 28 is removed.This allows each of the filaments 34 to form an isolated electrode, notan electrical contact with any other filament, that may be used formapping and ablation. Alternatively, specific filaments may be permittedto contact each other to form a preselected grouping.

Each of the filaments 34 is helically wound under compression aboutinner member 22. As a result of this helical construction, upon radialexpansion of braided conductive member 28, the portions of filaments 34that have had the insulation stripped away do not contact adjacentfilaments and thus, each filament 34 remains electrically isolated fromevery other filament. FIG. 6, in particular, illustrates how theinsulation may be removed from individual filaments 34 while stillproviding isolation between and among the filaments. As illustrated inFIG. 6, regions 50 illustrate regions, on the outer circumferentialsurface 60 of braided conductive member 28, where the insulation hasbeen removed from individual filaments 34. In one embodiment of theinvention, the insulation may be removed from up to one half of theouter facing circumference of each of the individual filaments 34 whilestill retaining electrical isolation between each of the filaments 34.

The insulation on each of the filaments 34 that comprise braidedconductive member 28 may be removed about the outer circumferentialsurface 60 of braided conductive member 28 in various ways. For example,one or more circumferential bands may be created along the length ofbraided conductive member 28. Alternatively, individual sectors orquadrants only may have their insulation removed about the circumferenceof braided conductive member 28. Alternatively, only selected filaments34 within braided conductive member 28 may have their circumferentiallyfacing insulation removed. Thus, an almost limitless number ofconfigurations of insulation removal about the outer circumferentialsurface 60 of braided conductive member 28 can be provided dependingupon the mapping and ablation characteristics and techniques that aclinician desires.

The insulation on each of the filaments 34 may be removed at the outercircumferential surface 60 of braided conductive member 28 in a varietyof ways as long as the insulation is maintained between filaments 34 sothat filaments 34 remain electrically isolated from each other.

The insulation can be removed from the filaments 34 in a variety of waysto create the stripped portions 50 on braided conductive member 28. Forexample, mechanical means such as abration or scraping may be used. Inaddition, a water jet, chemical means, or thermal radiation means may beused to remove the insulation.

In one example of insulation removal, braided conductive member 28 maybe rotated about inner member 22, and a thermal radiation source such asa laser may be used to direct radiation at a particular point along thelength of braided conductive member 28. As the braided conductive member28 is rotated and the thermal radiation source generates heat, theinsulation is burned off the particular region.

Insulation removal may also be accomplished by masking selected portionsof braided conductive member 28. A mask, such as a metal tube may beplaced over braided conducive member 28. Alternatively, braidedconductive member 28 may be wrapped in foil or covered with some type ofphotoresist. The mask is then removed in the areas in which insulationremoval is desired by, for example, cutting away the mask, slicing thefoil, or removing the photoresist. Alternatively, a mask can be providedthat has a predetermined insulation removal pattern. For example, ametal tube having cutouts that, when the metal tube is placed overbraided conductive member 28, exposes areas where insulation is to beremoved.

FIG. 6 illustrates how thermal radiation 52 may be applied to the outercircumferential surface 56 of a respective filament 34 that defines theouter circumferential surface 60 of braided conductive member 28. Asthermal radiation 52 is applied, the insulation 54 is burned off orremoved from the outer circumference 56 of wire 34 to create a region 58about the circumference 56 of filament 34 that has no insulation.

The insulation 54 can also be removed in a preferential manner so that aparticular portion of the circumferential surface 56 of a filament 34 isexposed. Thus, when braided conductive member 28 is radially expanded,the stripped portions of filaments may preferentially face the intendeddirection of mapping or ablation.

With the insulation removed from the portions of filaments 34 on theouter circumferential surface 60 of braided conductive member 28, aplurality of individual mapping and ablation channels can be created. Awire runs from each of the filaments 34 within catheter shaft 12 andcontrol handle 14 to connector portion 16. A multiplexer or switch boxmay be connected to the conductors so that each filament 34 may becontrolled individually. This function may be incorporated intocontroller 8. A number of filaments 34 may be grouped together formapping and ablation. Alternatively, each individual filament 34 can beused as a separate mapping channel for mapping individual electricalactivity within a blood vessel at a single point. Using a switch box ormultiplexer to configure the signals being received by filaments 34 orablation energy sent to filaments 34 results in an infinite number ofpossible combinations of filaments for detecting electrical activityduring mapping procedures and for applying energy during an ablationprocedure.

By controlling the amount of insulation that is removed from thefilaments 34 that comprise braided conductive member 28, the surfacearea of the braid that is in contact with a blood vessel wall can alsobe controlled. This in turn will allow control of the impedancepresented to an ablation energy generator, for example, generator 4. Inaddition, selectively removing the insulation can provide apredetermined or controllable profile of the ablation energy deliveredto the tissue.

The above description illustrates how insulation may be removed from afilaments 34. Alternatively, the same features and advantages can beachieved by adding insulation to filaments 34. For example, filaments 34may be bare wire and insulation can be added to them.

Individual control of the electrical signals received from filaments 34allows catheter 10 to be used for bipolar (differential or betweenfilament) type mapping as well as unipolar (one filament with respect toa reference) type mapping.

Catheter 10 may also have, as illustrated in FIGS. 2 and 3, a referenceelectrode 13 mounted on shaft 12 so that reference electrode 13 islocated outside the heart during unipolar mapping operations.

Radiopaque markers can also be provided for use in electrode orientationand identification.

One skilled in the art will appreciate all of the insulation can beremoved from filaments 34 to create a large ablation electrode.

Although a complete catheter steerable structure has been illustrated,the invention can also be adapted so that inner tubular member 22 is acatheter shaft, guide wire, or a hollow tubular structure forintroduction of saline, contrast media, heparin or other medicines, orintroduction of guidewires, or the like.

Temperature Sensing

A temperature sensor or sensors, such as, but not limited to, one ormore thermocouples may be attached to braided conductive member 28 fortemperature sensing during ablation procedures. A plurality ofthermocouples may also be woven into the braided conductive member 28.An individual temperature sensor could be provided for each of thefilaments 34 that comprise braided conductive member 28. Alternatively,braided conductive member 28 can be constructed of one or moretemperature sensors themselves.

FIG. 8 illustrates braided conductive member 28 in its fully expanded ordeployed configuration. Braided conductive member 28 forms a disk whenfully expanded. In the embodiment illustrated in FIG. 8, there aresixteen filaments 34 that make up braided conductive member 28.

Temperature monitoring or control can be incorporated into braidedconductive member 28, for example, by placing temperature sensors (suchas thermocouples, thermistors, etc.) on the expanded braided conductivemember 28 such that they are located on the distally facing ablativering formed when braided conductive member 28 is in its fully expandedconfiguration. “Temperature monitoring” refers to temperature reportingand display for physician interaction. “Temperature control” refers tothe capability of adding an algorithm in a feedback loop to titratepower based on temperature readings from the temperature sensorsdisposed on braided conductive member 28. Temperature sensors canprovide a means of temperature control provided the segment of theablative ring associated with each sensor is independently controllable(e.g., electrically isolated from other regions of the mesh). Forexample, control can be achieved by dividing the ablative structure intoelectrically independent sectors, each with a temperature sensor, oralternatively, each with a mechanism to measure impedance in order tofacilitate power titration. The ablative structure may be divided intoelectrically independent sectors so as to provide zone control. Theprovision of such sectors can be used to provide power control tovarious sections of braided conductive member 28.

As illustrated in FIG. 8, four temperature sensors 70 are provided onbraided conductive member 28. As noted previously, since the individualfilaments 34 in braided conductive member 28 are insulated from eachother, a number of independent sectors may be provided. A sector mayinclude one or more filaments 34. During ablation procedures, energy canbe applied to one or more of the filaments 34 in any combination desireddepending upon the goals of the ablation procedure. A temperature sensorcould be provided on each filament 34 of braided conductive member 28 orshared among one or more filaments. In mapping applications, one or moreof the filaments 34 can be grouped together for purposes of measuringelectrical activity. These sectoring functions can be provided incontroller 8.

FIG. 10 illustrates a side view of braided conductive member 28including temperature sensors 70. As shown in FIG. 10, temperaturesensors 70 emerge from four holes 72. Each hole 72 is disposed in onequadrant of anchor 74. The temperature sensors 70 are bonded to theoutside edge 76 of braided conductive member 28. Temperature sensors 70may be isolated by a small piece of polyimide tubing 73 around them andthen bonded in place to the filaments. The temperature sensors 7 may bewoven and twisted into braided conductive member 28 or they can bebonded on a side-by-side or parallel manner with the filaments 34.

There are several methods of implementing electrically independentsectors. In one embodiment, the wires are preferably stripped of theirinsulative coating in the region forming the ablative ring (whenexpanded). However, sufficient insulation may be left on the wires inorder to prevent interconnection when in the expanded state.Alternatively, adjacent mesh wires can be permitted to touch in theirstripped region, but can be separated into groups by fully insulated(unstripped) wires imposed, for example, every 3 or 5 wires apart (thenumber of wires does not limit this invention), thus forming sectors ofindependently controllable zones. Each zone can have its own temperaturesensor. The wires can be “bundled” (or independently attached) toindependent outputs of an ablation energy generator. RF energy can thenbe titrated in its application to each zone by switching power on andoff (and applying power to other zones during the ‘off period’) or bymodulating voltage or current to the zone (in the case of independentcontrollers). In either case, the temperature inputs from thetemperature sensors can be used in a standard feedback algorithm tocontrol the power delivery.

Alternatively, as illustrated in FIG. 10A, braided conductive member 28may be used to support a ribbon-like structure which is separated intodiscrete sectors. As shown in FIG. 10A, the ribbon-like structure 81 maybe, for example, a pleated copper flat wire that, as braided conductivemember 28 expands, unfolds into an annular ring. Each of the wires 83a-83 d lie in the same plane. Although four wires are illustrated inFIG. 10A, structure 81 may include any number of wires depending uponthe application and desired performance. Each of wires 83 a-83 d isinsulated. Insulation may then be removed from each wire to createdifferent sectors 85 a-85 d. Alternatively, each of wires 83 a-83 d maybe uninsulated and insulation may be added to create different sectors.The different sectors provide an ablative zone comprised ofindependently controllable wires 83 a-83 d. Temperature sensors 70 maybe mounted on the individual wires, and filaments 34 may be connected torespective wires 83 a-83 d to provide independent control of energy toeach individual sector. One skilled in the art will appreciate that eachof wires 83 a-83 d can have multiple sectors formed by removinginsulation in various locations and that numerous combinations ofsectors 85 a-85 d and wires 83 a-83 d forming ribbon-like structure 81can be obtained.

Steering

Reference is now made to FIGS. 11-13 which illustrate aspects of thesteering capabilities of the present invention. As illustrated in FIGS.1-2, catheter 10 is capable of being steered using control handle 14. Inparticular, FIG. 1 illustrates steering where the steering pivot orknuckle is disposed on catheter shaft 12 in a region that is distal tothe braided conductive member 28.

FIG. 11 illustrates catheter 10 wherein the pivot point or steeringknuckle is disposed proximal to braided conductive member 28.

FIG. 12 illustrates catheter 10 having the capability of providingsteering knuckles both proximal and distal to braided conductive member28.

FIGS. 1-2, and 11-12 illustrate two dimensional or single plane typesteering. The catheter of the present invention can also be used inconnection with a three dimensional steering mechanism. For example,using the control handle in the incorporated by reference '852 patent,the catheter can be manipulated into a three-dimensional “lasso-like”shape, particularly at the distal end of the catheter. As shown in FIG.13, the catheter can have a primary curve 80 in one plane and then asecond curve 82 in another plane at an angle to the first plane. Withthis configuration, the catheter can provide increased access todifficult to reach anatomical structures. For example, a target site fora mapping or ablation operation may be internal to a blood vessel. Thus,the increased steering capability can allow easier access into thetarget blood vessel. In addition, the additional dimension of steeringcan allow for better placement of braided conductive member 28 during anablation or mapping procedure. Catheter 10 can be inserted into a siteusing the steering capabilities provided by primary curve 80.Thereafter, using the secondary curve 82, braided conductive member 28can be tilted into another plane for better orientation or contact withthe target site.

Conductive Member Configurations And Materials

Reference is now made to FIGS. 14-17 which figures illustrate otherconfigurations of braided conductive member 28. As has been describedabove and will be described in more detail, braided conductive member 28can include from one to 300 or more filaments. The filaments may varyfrom very fine wires having small diameters or cross-sectional areas tolarge wires having relatively large diameters or cross-sectional areas.

FIG. 14 illustrates the use of more than one braided conductive member28 as the distal end of catheter 10. As shown in FIG. 14, three braidedconductive members 28A, 28B, and 28C are provided at the distal end ofcatheter 10. Braided conductive members 28A, 28B, and 29C may be, intheir expanded conditions, the same size or different sizes. Each of thebraided conductive members 28A, 28B, and 28C can be expanded orcontracted independently in the manner illustrated in FIGS. 1-4 viaindependent control shafts 26A, 26B, and 26C. The use of multiplebraided conductive members provides several advantages. Rather thanhaving to estimate or guess as to the size of the blood vessel prior tostarting a mapping or ablation procedure, if braided conductive members28A, 28B, and 28C are of different expanded diameters, than sizing canbe done in vivo during a procedure. In addition, one of the braidedconductive members can be used for ablation and another of the braidedconductive members can be used for mapping. This allows for quicklychecking the effectiveness of an ablation procedure.

Reference is now made to FIGS. 15A and 15B, which figures illustrateother shapes of braided conductive member 28. As described up to thispoint, braided conductive member 28 is generally symmetrical and coaxialwith respect to catheter shaft 12. However, certain anatomicalstructures may have complex three-dimensional shapes that are not easilyapproximated by a geometrically symmetrical mapping or ablationstructure. One example of this type of structure occurs at the CSostium. To successfully contact these types of anatomical structures,braided conductive member 28 can be “preformed” to a close approximationof that anatomy, and yet still be flexible enough to adapt to variationsfound in specific patients. Alternatively, braided conductive member 28can be “preformed” to a close approximation of that anatomy, and be ofsufficient strength (as by choice of materials, configuration, etc.) toforce the tissue to conform to variations found in specific patients.For example FIG. 15A illustrates braided conductive member 28 disposedabout shaft 12 in an off-center or non concentric manner. In addition,braided conductive member 28 may also be constructed so that theparameter of the braided conductive member in its expanded configurationhas a non-circular edge so as to improve tissue contact around theparameter of the braided conductive member. FIG. 15B illustrates anexample of this type of configuration where the braided conductivemember 28 is both off center or non concentric with respect to cathetershaft 12 and also, in its deployed or expanded configuration, has anasymmetric shape. The eccentricity of braided conductive member 28 withrespect to the shaft and the asymmetric deployed configurations can beproduced by providing additional structural supports in braidedconductive member 28, for example, such as by adding nitinol, ribbonwire, and so on. In addition, varying the winding pitch or individualfilament size or placement or deforming selective filaments in braidedconductive member 28 or any other means known to those skilled in theart may be used.

FIGS. 16A-16C illustrate another configuration of braided conductivemember 28 and catheter 10. As illustrated in FIGS. 16A-16C, the distaltip section of catheter 10 has been removed and braided conductivemember 28 is disposed at the distal end of catheter 10. One end ofbraided conductive member 28 is anchored to catheter shaft 12 using ananchor band 90 that clamps the end 32 of braided conductive member 28 tocatheter shaft 12. The other end of braided conductive member 28 isclamped to an activating shaft such as shaft 26 using another anchorband 92. FIG. 16A illustrates braided conductive member 28 in itsundeployed configuration. As shaft 26 is moved distally, braidedconductive member 28 emerges or everts from shaft 12. As shown in FIG.16B, braided conductive member 28 has reached its fully deployeddiameter and an annular tissue contact zone 29 can be placed against anostium or other anatomical structure. As illustrated in FIG. 16C,further distal movement of shaft 26 can be used to create a concentriclocating region 94 that can help to provide for concentric placementwithin an ostium of a pulmonary vein, for example. Concentric locatingregion 94 may be formed by selective variations in the winding densityof filaments 34 in braided conductive member 28, preferentialpredeformation of the filaments, additional eversion of braidedconductive member 28 from shaft 12, or by other means known to thoseskilled in the art.

Reference is now made to FIG. 17, which figure illustrates a furtherembodiment of braided conductive member 28. As illustrated in FIG. 17,braided conductive member 28 is composed of one or several large wires96 rather than a multiplicity of smaller diameter wires. The wire orwires can be moved between the expanded and unexpanded positions in thesame manner as illustrated in FIG. 1. In addition, a region 98 may beprovided in which the insulation has been removed for mapping orablation procedures. The single wire or “corkscrew” configurationprovides several advantages. First, the wire or wires do not cross eachother and therefore there is only a single winding direction requiredfor manufacture. In addition, the risk of thrombogenicity may be reducedbecause there is a smaller area of the blood vessel being blocked. Inaddition, the connections between the ends of the large wire and thecontrol shafts may be simplified.

The catheter 10 of the present invention can be coated with a number ofcoatings that can enhance the operating properties of braided conductivemember 28. The coatings can be applied by any of a number of techniquesand the coatings may include a wide range of polymers and othermaterials.

Braided conductive member 28 can be coated to reduce its coefficient offriction, thus reducing the possibility of thrombi adhesion to thebraided conductive member as well as the possibility of vascular oratrial damage. These coatings can be combined with the insulation on thefilaments that make up braided conductive member 28, these coatings canbe included in the insulation itself, or the coatings can be applied ontop of the insulation. Examples of coating materials that can be used toimprove the lubricity of the catheter include PD slick available fromPhelps Dodge Corporation, Ag, Tin, BN. These materials can be applied byan ion beam assisted deposition (“IBAD”) technique developed by, forexample, Amp Corporation.

Braided conductive member 28 can also be coated to increase or decreaseits thermal conduction which can improve the safety or efficacy of thebraided conductive member 28. This may be achieved by incorporatingthermally conductive elements into the electrical insulation of thefilaments that make up braided conductive member 28 or as an addedcoating to the assembly. Alternatively, thermally insulating elementsmay be incorporated into the electrical insulation of the filaments thatmake up braided conductive member 28 or added as a coating to theassembly. Polymer mixing, IBAD, or similar technology could be used toadd Ag, Pt, Pd, Au, Ir, Cobalt, and others into the insulation or tocoat braided conductive member 28.

Radioopaque coatings or markers can also be used to provide a referencepoint for orientation of braided conductive member 28 when viewed duringfluoroscopic imaging. The materials that provide radiopacity including,for example, Au, Pt, Ir, and other known to those skilled in the art.These materials may be incorporated and used as coatings as describedabove.

Antithrombogenic coatings, such as heparin and BH, can also be appliedto braided conductive member 28 to reduce thrombogenicity to preventblood aggregation on braided conductive member 28. These coatings can beapplied by dipping or spraying, for example.

As noted above, the filament 34 of braided conductive member 28 may beconstructed of metal wire materials. These materials may be, forexample, MP35N, nitinol, or stainless steel. Filaments 34 may also becomposites of these materials in combination with a core of anothermaterial such as silver or platinum. The combination of a highlyconductive electrical core material with another material forming theshell of the wire allows the mechanical properties of the shell materialto be combined with the electrical conductivity of the core material toachieve better and/or selectable performance. The choice and percentageof core material used in combination with the choice and percentage ofshell material used can be selected based on the desired performancecharacteristics and mechanical/electrical properties desired for aparticular application.

Irrigation

It is known that for a given electrode side and tissue contact area, thesize of a lesion created by radiofrequency (RF) energy is a function ofthe RF power level and the exposure time. At higher powers, however, theexposure time can be limited by an increase in impedance that occurswhen the temperature at the electrode-tissue interface approaches a 100°C. One way of maintaining the temperature less than or equal to thislimit is to irrigate the ablation electrode with saline to provideconvective cooling so as to control the electrode-tissue interfacetemperature and thereby prevent an increase in impedance. Accordingly,irrigation of braided conductive member 28 and the tissue site at whicha lesion is to be created can be provided in the present invention. FIG.18 illustrates the use of an irrigation manifold within braidedconductive member 28. An irrigation manifold 100 is disposed along shaft22 inside braided conductive member 28. Irrigation manifold 100 may beone or more polyimid tubes. Within braided conductive member 28, theirrigation manifold splits into a number of smaller tubes 102 that arewoven into braided conductive member 28 along a respective filament 34.A series of holes 104 may be provided in each of the tubes 102. Theseholes can be oriented in any number of ways to target a specific site orportion of braided conductive member 28 for irrigation. Irrigationmanifold 100 runs through catheter shaft 12 and may be connected to anirrigation delivery device outside the patient used to inject anirrigation fluid, such as saline, for example, such as during anablation procedure.

The irrigation system can also be used to deliver a contrast fluid forverifying location or changes in vessel diameter. For example, acontrast medium may be perfused prior to ablation and then after anablation procedure to verify that there have been no changes in theblood vessel diameter. The contrast medium can also be used duringmapping procedures to verify placement of braided conductive member 28.In either ablation or mapping procedures, antithrombogenic fluids, suchas heparin can also be perfused to reduce thrombogenicity.

FIG. 19 illustrates another way of providing perfusion/irrigation incatheter 10. As illustrated in FIG. 19, the filaments 34 that comprisebraided conductive member 28 are composed of a composite wire 110. Thecomposite wire 110 includes an electrically conductive wire 112 that isused for delivering ablation energy in an ablation procedure or fordetecting electrical activity during a mapping procedure. Electricalwire 112 is contained within a lumen 114 that also contains a perfusionlumen 116. Perfusion lumen 116 is used to deliver irrigation fluid or acontrast fluid as described in connection with FIG. 18. Once braidedconductive member 28 has been constructed with composite wire 110, theinsulation 118 surrounding wire filament 112 can be stripped away toform an electrode surface. Holes can then be provided into perfusionlumen 116 to then allow perfusion at targeted sites along the electrodesurface. As with the embodiment illustrated in FIG. 18, the perfusionlumens can be connected together to form a manifold which manifold canthen be connected to, for example, perfusion tube 120 and connected to afluid delivery device.

Shrouds

The use of a shroud or shrouds to cover at least a portion of braidedconductive member 28 can be beneficial in several ways. The shroud canadd protection to braided conductive member 28 during insertion andremoval of catheter 10. A shroud can also be used to form or shapebraided conductive member 28 when in its deployed state. Shrouds mayalso reduce the risk of thrombi formation on braided conductive member28 by reducing the area of filament and the number of filament crossingsexposed to blood contact. This can be particularly beneficial at theends 30 and 32 of braided conductive member 28. The density of filamentsat ends 30 and 32 is greatest and the ends can therefore be prone toblood aggregation. The shrouds can be composed of latex balloon materialor any material that would be resistant to thrombi formation durableenough to survive insertion through an introducer system, and would notreduce the mobility of braided conductive member 28. The shrouds canalso be composed of an RF transparent material that would allow RFenergy to pass through the shroud. If an RF transparent material isused, complete encapsulation of braided conductive member 28 ispossible.

A shroud or shrouds may also be useful when irrigation or perfusion isused, since the shrouds can act to direct irrigation or contrast fluidto a target region.

FIGS. 20A-20E illustrate various examples of shrouds that may be used inthe present invention. FIG. 20A illustrates shrouds 130 and 132 disposedover end regions 31 and 33, respectively, of braided conductive member28. This configuration can be useful in preventing coagulation of bloodat the ends of braided conductive member 28. FIG. 20B illustratesshrouds 130 and 132 used in conjunction with an internal shroud 134contained inside braided conductive member 28. In addition to preventingblood coagulation in regions 31 and 32, the embodiment illustrated inFIG. 20B also prevents blood from entering braided conductive member 28.

FIG. 20C illustrates shrouds 130 and 132 being used to direct andirrigation fluid or contrast medium along the circumferential edge ofbraided conductive member 28. In the embodiment illustrated in FIG. 20C,perfusion can be provided as illustrated in FIGS. 18 and 19.

FIG. 20D illustrates the use of an external shroud that covers braidedconductive member 28. Shroud 136 completely encases braided conductivemember 28 and thereby eliminates blood contact with braided conductivemember 28. Shroud 136 may be constructed of a flexible yetablation-energy transparent material so that, when used in an ablationprocedure, braided conductive member 28 can still deliver energy to atargeted ablation site.

FIG. 20E also illustrates an external shroud 137 encasing braidedconductive member 28. Shroud 137 may also be constructed of a flexibleyet ablation-energy transparent material. Openings 139 may be providedin shroud 137 to allow the portions of braided conductive member 28 thatare exposed by the opening to come into contact with tissue. Openings139 may be elliptical, circular, circumferential, etc.

Guiding Sheaths

There may be times during ablation or mapping procedures when catheter10 is passing through difficult or tortuous vasculature. During thesetimes, it may be helpful to have a guiding sheath through which to passcatheter 10 so as to allow easier passage through the patient'svasculature.

FIG. 21 illustrates one example of a guiding sheath that may be used inconnection with catheter 10. As illustrated in FIG. 21, the guidingsheath 140 includes a longitudinal member 142. Longitudinal member 142may be constructed of a material rigid enough to be pushed next tocatheter shaft 12 as the catheter is threaded through the vasiculature.In one example, longitudinal member 142 may be stainless steel.Longitudinal member 142 is attached to a sheath 144 disposed at thedistal end 146 of longitudinal member 142. The split sheath 144 may haveone or more predetermined curves 148 that are compatible with the shapesof particular blood vessels (arteries or veins) that catheter 10 needsto pass through. Split sheath 144 may extend proximally alonglongitudinal member 142. For example, sheath 144 and longitudinal member142 may be bonded together for a length of up to 20 or 30 centimeters toallow easier passage through the patient's blood vessels. Sheath 144includes a predetermined region 150 that extends longitudinally alongsheath 144. Region 150 may be, for example, a seam, that allows sheath144 to be split open so that the guiding sheath 140 can be pulled backand peeled off catheter shaft 12 in order to remove the sheath.

In another embodiment, longitudinal member 142 may be a hypotube or thelike having an opening 152 at distal end 146 that communicates with theinterior of sheath 144. In this embodiment, longitudinal member 142 canbe used to inject irrigation fluid such as saline or a contrast mediumfor purposes of cooling, flushing, or visualization.

Methods of Use

Reference is now made to FIGS. 22, 23, and 24, which figures illustratehow the catheter of the present invention may be used in endocardial andepicardial applications.

Referring to FIG. 22, this figure illustrates an endocardial ablationprocedure. In this procedure, catheter shaft 12 is introduced into apatient's heart 150. Appropriate imaging guidance (direct visualassessment, camera port, fluoroscopy, echocardiographic, magneticresonance, etc.) can be used. FIG. 22 in particular illustrates cathetershaft 12 being placed in the left atrium of the patient's heart. Oncecatheter shaft 12 reaches the patient's left atrium, it may then beintroduced through an ostium 152 of a pulmonary vein 154. Asillustrated, braided conductive member 28 is then expanded to itsdeployed position, where, in the illustrated embodiment, braidedconductive member 28 forms a disk. Catheter shaft 12 then advancedfurther into pulmonary vein 154 until the distal side 156 of braidedconductive member 28 makes contact with the ostium of pulmonary vein154. External pressure may be applied along catheter shaft 12 to achievethe desired level of contact of braided conductive member 28 with theostium tissue. Energy is then applied to the ostium tissue 152 incontact with braided conductive member 28 to create an annular lesion ator near the ostium. The energy used may be RF (radiofrequency), DC,microwave, ultrasonic, cryothermal, optical, etc.

Reference is now made to FIG. 23, which figure illustrates an epicardialablation procedure. As illustrated in FIG. 23, catheter shaft 12 isintroduced into a patient's thoracic cavity and directed to pulmonaryvein 154. Catheter 10 may be introduced through a trocar port orintraoperatively during open chest surgery Using a steering mechanism,preformed shape, or other means by which to make contact between braidedconductive member 128 and the outer surface 158 of pulmonary vein 154,braided conductive member 28 is brought into contact with the outersurface 158 of pulmonary vein 154. Appropriate imaging guidance (directvisual assessment, camera port, fluoroscopy, echocardiographic, magneticresonance, etc.) can be used. As illustrated in FIG. 23, in thisprocedure, braided conductive member 28 remains in its undeployed orunexpanded condition. External pressure maybe applied to achieve contactbetween braided conductive member 28 with pulmonary vein 154. Once thedesired contact with the outer surface 158 of pulmonary vein 154 isattained, ablation energy is applied to surface 158 via braidedconductive member 28 using, for example, RF, DC, ultrasound, microwave,cryothermal, or optical energy. Thereafter, braided conductive member 28may be moved around the circumference of pulmonary vein 154, and theablation procedure repeated. This procedure may be used to create, forexample, an annular lesion at or near the ostium.

Use of the illustrated endocardial or epicardial procedures may beeasier and faster than using a single “point” electrode since a completeannular lesion may be created in one application of RF energy.

Reference is now made to FIG. 24 which figure illustrates an endocardialmapping procedure. In the procedure illustrated in FIG. 24, cathetershaft 12 is introduced into pulmonary vein 154 in the manner describedin connection with FIG. 22. Once braided conductive 28 has reached adesired location within pulmonary vein 154, braided conductive member 28is expanded as described in connection with, for example, FIGS. 2-5until filaments 34 contact the inner wall 160 of pulmonary vein 154.Thereafter, electrical activity within pulmonary vein 154 may bedetected, measured, and recorded by an external device connected to thefilaments 34 of braided conductive member 28.

Access to the patient's heart can be accomplished via percutaneous,vascular, surgical (e.g. open-chest surgery), or transthoracicapproaches for either endocardial or epicardial mapping and/or mappingand ablation procedures.

The present invention is thus able to provide an electrophysiologycatheter capable of mapping and/or mapping and ablation operations. Inaddition, the catheter of the invention may be used to provide highdensity maps of a tissue region because electrocardiograms may beobtained from individual filaments 34 in braided conductive member 28 ineither a bipolar or unipolar mode.

Furthermore, the shape of the electrode region can be adjusted bycontrolling the radial expansion of braided conductive member 28 so asto improve conformity with the patient's tissue or to provide a desiredmapping or ablation profile. Alternatively, braided conductive member 28may be fabricated of a material of sufficient flexural strength so thatthe tissue is preferentially conformed to match the expanded orpartially expanded shape of the braided conductive member 28.

The catheter of the present invention may be used for mappingprocedures, ablation procedures, and temperature measurement and controlon the distal and/or proximal facing sides of braided conductive member28 in its fully expanded positions as illustrated in, for example,FIG. 1. In addition, the catheter of the present invention can be usedto perform “radial” mapping procedures, ablation procedures, andtemperature measurement and control. That is, the outer circumferentialedge 76, illustrated, for example, in FIG. 8, can be applied against aninner circumferential surface of a blood vessel.

Furthermore, being able to use the same catheter for both mapping andablation procedures has the potential to reduce procedure time andreduce X-ray exposure.

The ability to expand braided conductive member 28 in an artery or veinagainst a tissue structure such as a freewall or ostium can provide goodcontact pressure for multiple electrodes and can provide an anatomicalanchor for stability. Temperature sensors can be positioned definitivelyagainst the endocardium to provide good thermal conduction to thetissue. Lesions can be selectively produced at various sections aroundthe circumference of braided conductive member 28 without having toreposition catheter 10. This can provide more accurate lesion placementwithin the artery or vein.

Braided conductive member 28, in its radially expanded position asillustrated in particular in FIGS. 1 and 8 is advantageous because, inthese embodiments, it does not block the blood vessel during a mappingor ablation procedure, but allows blood flow through the braidedconductive member thus allowing for longer mapping and/or ablationtimes, which can potentially improve accuracy of mapping and efficacy oflesion creation.

Having thus described at least one illustrative embodiment of theinvention, various alterations, modifications, and improvements willreadily occur to those skilled in the art. Such alterations,modifications, and improvements are intended to be within the spirit andscope of the invention. Accordingly, the foregoing description is by wayof example only and is not intended as limiting. The invention islimited only as defined in the following claims and the equivalentsthereto.

1. A medical device for electrophysiology procedures, comprising: abraided conductive member having a first end and a second end; a firstcatheter shaft having an extreme distal end wherein the first end of thebraided conductive member is attached to the extreme distal end of thecatheter shaft; a second catheter shaft having an extreme distal endwherein he second end of the braided conductive member is attached tothe extreme distal end of the second catheter shaft and wherein thesecond catheter shaft is contained within the first catheter shaft; sothat in an undeployed position, the braided conductive member issubstantially contained within the first catheter shaft; and when theextreme distal end of the first catheter shaft is substantially alignedwith the extreme distal end of the second catheter shaft, the braidedconductive member is in a deployed position.
 2. The medical device ofclaim 1, wherein the braided conductive member is a wire mesh.
 3. Themedical device of claim 2, wherein the wire mesh includes a number offilaments.
 4. The medical device of claim 3, further comprising acoating material disposed on at least a portion of the wire mesh.
 5. Themedical device of claim 3, further comprising an irrigation system thatdelivers an irrigation fluid in proximity to the braided conductivemember.
 6. The medical device of claim 3, further comprising atemperature sensing device attached to the braided conductive member. 7.The medical device of claim 3, further comprising a shroud that coversat least a portion of the braided conductive member when the braidedconductive member is in the deployed position.
 8. The medical device ofclaim 1, wherein the braided conductive member further comprises aconcentric locating region when the braided conductive member is in thedeployed position.
 9. The medical device of claim 1, further comprisinga hollow tubular lumen within the catheter.